1. Field of Invention
The present invention relates to a semiconductor device and a manufacturing method thereof. More particularly, the present invention relates to an anti-punch-through semiconductor device and a manufacturing method thereof.
2. Description of Related Art
Along with the rapid development of the integrated circuit industry and the trend of high integration, the size of the entire circuit device is forced to be minimized to meet the requirement. When the size of the semiconductor reduces gradually, the distance between devices also relatively reduces. When the distance reduces to some degree, the process problem due to the high integration of device may occur. Therefore, it is a common objective in the industry to produce a semiconductor device with small size, high integration and high quality.
FIG. 1 is a schematic cross-sectional view of a conventional trench device. Referring to FIG. 1A, a plurality of trenches 102 is formed in the substrate 100, and the trench device is disposed in the trench 102. The trench devices are trench memories, and the trench memories includes a floating gate 104, a dielectric layer 106, and a control gate 108. Moreover, the trench device further includes a source/drain region 110 disposed in the substrate under the floating gate 104, the dielectric layer 106 and the control gate 108.
However, along with increased integration, in the process of forming the gate made of doped polysilicon, the dopant may diffuse into the source/drain region 110 to extend the region, which may easily cause the abnormal electric punch-through in the adjacent source/drain regions 110. The problem of the electric punch-through may cause abnormal electric connection between adjacent trench devices, which may result in low operation speed and low performance efficiency, and even short or open circuit of the devices. Accordingly, the yield and reliability of the whole process are adversely affected.